That plant is shocked either your grow room is to cold so shes not developing as fast or humidity are to low make sure atleast your dirt/pot isnt cold as hell cus ur slowing the roots respiratory system and it slows down feeding and nutrient uptake so the plant suffers 2 weeks should be bigger , i only grew for a month and half and im 26 days into flower with cfl 100 watts each 5000 k i take her out to the sun for 3 hours a day atleast i have an indoor an outdoor grow